1. Field of the Invention
This invention relates generally to water filter or treatment systems, and, more specifically, to systems including intermediate storage for filtered or treated water.
2. Related Art
Conventional filter systems permit water to flow in a single pass through filter or treatment media to a storage tank, water tap, or other usage device. When additional filtering of stored water is desired to remove contamination or biocides immediately before use, conventional systems typically require multiple filter canisters and complicated valving and piping.
Reid (U.S. Pat. No. 5,248,417) discloses a double-flow-through system using a single filter housing. In this system, water flows through a single bed of filter media and then through a combination outlet-inlet port to a storage tank. When a tap or faucet is opened, the stored water flows back through the combination port into the filter housing to flow again through the filter media bed and then out to the tap. Thus, the Reid '417 system provides two passes through a single bed of filter media, with intermediate storage between the two passes.
The Reid '417 apparatus includes a pair of check valves to control flow to and from the combination port, and, thus, to and from storage. When the water tap is closed, unfiltered water enters the upper portion of the filter housing through the inlet port and is prevented by a cup-type check valve from flowing directly to the combination outlet-inlet port. The water passes a first time through the media and flows up through a filter tube to the combination port. A slit-type check valve disposed at the top of the filter tube prevents water from flowing from the combination port back into the filter tube. Once the water tap is opened, the cup-style check valve allows water to flow from storage through the combination port, through the cup check valve into the top portion of the filter housing, through the media a second time, and then to the tap.
Reid (U.S. Pat. No. 5,232,590) discloses a water filtration apparatus with an internal by-pass for conducting water from a water source to a storage tank without passing through the filter media. When the tap or faucet is opened, water then flows back from the storage tank into the filter housing, through the filter media, out the outlet port, and out of the faucet.
Grayson, et al. (U.S. Pat. No. 5,082,557) discloses a filter control head for directing water to various locations. The control head can direct water to a first filter canister, to a drain, and to a storage tank. When a downstream usage device demands water, purified water may then flow from the storage tank, back to the control head, and then to a separate, second filter canister and a downstream usage device.